Polymerization of perhalocarbons with chloropropionyl peroxides



March 5, 1957 Filed Dec. 21, 1954 A. DITTMAN ET AL 2,784,176 POLYMERIZATION OF PERHALOCARBONS WITH CHLOROFROPIONYL. PEROXIDES 3 Sheets-Sheet 1 +l\o c O o c 0 0.0l 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.l0 0.|l

CONCENTRATION OF TRIFLUORODICHLOROPROPIONYL PEROXIDE FIGI [3 H 9 I/ v 0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 O.l0 'O.Il

CONCENTRATION OF TRIFLUORODICHLOROPROPIONYL PEROXIDE lNVENTQRS ALBERT L. DITTMAN JOHN M. WRIGHTSON March 5, 1957 Filed Dec.

N. S.T. C

In YIELD A. L. DITTMAN ETAL 2,784,176 POLYMERIZATION OF PERHALOCARBONS WITH CHLOROPROPIONYL PEROXIDES 3 Sheets-Sheet 2 O 5 l0 TEMP.C (WITH TRIFLUORODICHLOROPIONYL PEROXIDE) FIG. 3

o 5 IO TEMP5C (WITH TRIFLUORODICHLOROPIONYL PEROXIDE) FIG.4

INVENTORS ALBERT L. DITTMAN JOHN M. WRIGHTSON ATTORiEYZ March 1957 A. DITTMAN ET AL 2,784,176

POLYMERIZATION OF PERHALOCARBONS WITH CHLOROPROFIONYL PEROXIDES D90. 21, 1954 3 She'ets-Sheet 3 O 2 4 6 8 l0 l2 l4 l6 I8 20 22 24 YIELD (WITH 0.015% TRIFLUORODICHLOROPROPIONYL PEROXIDE FIG. 5

o 2 4 e B IO 12 I4 l5l3 202224 TIME IN HOURS(WITH o.o|5% TRIFLUORODICHLOROPROPIONYL PEROXIDE) FIG.6

+|oc 12 IO l a OC 6 YIELD 0 2 4 6 8 IO l2 l4 I6 18 2O 22 24 TIME IN HOURS- NVENTORS I (WITH 0.015% TRIFLUORODICHLOROPROPIONYL PEROXIDE) ALBERT L.DITTMAN JOHN M.W IGHTSON FIG. 7 BY M ATTORN YS POLYMERIZATIUN @F PERHALOCAREZONS WHH CHLOROPROPIONYL PEROXIDES Albert L. Dittman, North Bergen, N. 3., and John M. Wrightson, Whittier, Calih, assignors to The M. W. Kellogg Company, Jersey City, N. 3., a corporation of Delaware Application December 21, 1954, Serial No. 476,786

10 Claims. (Cl. Mil-92.1)

This invention relates to the manufacture of perhalocarbons. In one of its aspects, the invention relates to the manufacture of perhalocarbon plastics, oils, greases and waxes. More particularly in this aspect, the invention relates to a method for the polymerization of perhalo-olefins to produce normally liquid and solid perhalopolymers. Still more particularly in this latter aspect, the invention relates to a method for the polymerization of trifiuorochloroethylene to produce normally liquid and solid polymers of this monomer.

This application is a continuation-in-part of our prior and co-pending application Serial No. 225,850, filed May 11, 1951, Patent No. 2,705,706, issued April 5, 1955.

Normally liquid and solid perhalocarbons have been produced by the polymerization of a monomer in the presence of certain promoters, and, in the case of liquids, also in the presence of a chain-transfer solvent. For example, under suitable conditions of temperature and residence time, and in the presence of trichloroacetyl peroxide, trifiuorochloroethylene can be polymerized to obtain chemically and physically stable, solid polymers having a variety of uses. Benzoyl peroxide has been employed to produce liquid polymers. The disadvantage of these promoters in comparison with the promoters of the present invention, resides in their being more expensive to produce, and in being unstable at relatively high temperatures. In the case of benzoyl peroxide, there is the further disadvantage that the fragments of promoter attached to the polymer contain hydrogen which makes the polymer less stable.

It is, therefore, an object of the present invention to polymerize perhalo-oletins under suitable conditions in the presence of a new promoter to produce perhalopolymers.

Another object of the invention is to provide an improved method for producing perhalo-olefin polymers of predetermined chemical and physical characteristics and high yields.

Still another object of the invention is to provide an improved method for producing polymers of trifluorochloroethylene.

A further object of the invention is to provide a novel promoter suitable for use in the polymerization of perhalo-olefins to produce perhalo-polymers.

A still further object of the invention is toprovide a method for producing a novel promoter suitable for use in the polymerization of perhalo-olefins to produce perhalo-polymers.

Various other objects and advantages of the present invention will become apparent to those'skilled in the art from the accompanying description and disclosure.

As herein employed, perhalocarbons are defined as compounds consisting substantially exclusively of carbon States Patent and halogen with any degree of unsaturation and containing only negligible amounts of other elements, such as hydrogen and oxygen, in a quantity less than about 2 weight percent as impurities. These other elements are derived from materials utilized in the process as will hereinafter become apparent. Perhalo-olefins are defined as perhalo-olefins having any degree of unsaturation, and consisting of halogens and carbon. Perfluoro-olefins are defined as perhalo-olefins having any degree of unsaturation and consisting of fluorine and carbon. .Perfiuorochloro-olefinsare defined as perhalo-olefins consisting of fluorine, chlorine andcarbon. vThepreferred perfiuorochloro-olefins of this invention are those containing not more than one chlorine atom per carbon atom.

According to this invention, perhalo-olefins are homopolymerized or copolymerized under suitable polymerization conditions in the presence of a halogenated acyl peroxide as a promoter, to produce oils and greases at normal atmospheric temperature, and Waxes, including hard waxes having softening points extending to about 200 C., and normally solid material of the nature of thermoplastics, in high yields with good selectivity for the desired product.

The perhalo-olefins which may be homopolymerized or copolymerized in accordance with the process of the invention include perfiuoro-olefins and pcrfiuorochloroolefins, such as trifluorochloroethylene, tetrafiuoroethylene, perfiuorobutadiene, difluorodichloroethylene including both CF2=CC12 and CFC1=CFC1, perfluoropropene, perfluoromonochloropropene, perfiuorobutene, perfluoromonochlorobutene, diphenyldifiuoroethylene, etc. Typical examples of copolymerization of the above perhaloolefins include the copolymerization of trifluorochloroethylene and fluorochloroisooutene; of trifiuorochloroethylene and diphenyl-difiuoroethylene; of trifluorochloroethylene and tetrafluoroethylene; of trifluorochloroethylene and vinylidene fluoride; of trifluorochloroethylene and vinyl fluoride; of trifiuorochloroethylene and vinyl chloride; of trifiuorochloroethylene and vinylidene chloride; of trifiuorochloroethylene and periluoropropene; of trifluorochloroethylene and trifluoroethylene; and of perfluorobutadiene and perfiuorostyrene, etc.

The term polymerization includes, in its broadest sense, both homopolymerization and copolymerization of the perhalo-olefins with other compounds. In instances Where homopolymerization-is soughtto be carried out, as much as 5 percent of acomonomer, which does not necessarily affect the characteristics of the product, but which is used as a modifier, may be present.

Diphenyldifluoroethylene, useful for effecting the aforementioned copolymerization with trifluorochloroethylene may be prepared by the following series of reactions. in Equation I, following, chloral was reacted with hydro- .gen fluoride and mercuric oxide, in accordance with the indicated stoichiornetricalrequirements, to obtain monochiorodiiluoroacetaldehyde.

EQUATION 1 ll ll CCls-C-H 2HF HgO r GOlFi C-H HgCh H1O chloral monochlorodifluoro acetaldehyde The aqueous mixture of monochlorodifiuoro acetaldehyde, separated from the product recovered in Equation 1, above, was next reacted, according toEquation II, following, with benzene, according to .theincl-icated stoichio metrical requirements, in the presence of sulfuric acid as a catalyst to produce diphenyldifluorochloroethane.

EQUATION II diphenyldifluorochloroethane The melting point of the above-mentioned diphenyldifluorochloroethane product was found to be 42 C. The following analytical data were obtained for this com- This compound was next subjected to dehydrochlorination, employing potassium hydroxide in the presence of dioxane and water, according to Equation HI, following, in accordance with stoichiometrical requirements, to produce the desired diphenyldifluoroethylene, as a product v of the process.

EQUATION III diphenyldifiuord chloroethane ethylene The above-mentioned dehydrochlorination reaction was continued until the theoretical requirement of chlorine (01-) was produced along with a heavy oil. This oil was distilled through a small unpacked column at 0.3

mm. to obtain a major fraction boiling between about 7 75 C. and about 85 C.

In the polymerization of trifiuorochloroethylene, to which this invention has particular application, to produce either normally liquid or solid perhalo-polymers, the promoter employed is a major factor in elfecting the polymerization and determining the molecular weight, yield and characteristics of the product produced. According to the invention, as indicated above, polymerization or copolymerization of perhalo-olefins is carried out in the presence of a halogenated acyl peroxide, such as trifluorodichloropropionyl peroxide, as a promoter. amples of such promoters include halogen-substituted propionyl peroxides containing only chlorine substitution, such as perchloropropionyl peroxide and tetrachloropropiony-l peroxide.

The concentration of the halogenated acyl peroxide, used as a promoter in accordance with the process of the invention, is important in determining the molecular weight, yield and'characteristics of the product produced. In the case of producing normally solid polymers of the nature of thermoplastics, the amount of promoter used usually varies between about 0.01 and about 0.5 weight percent of the monomer in the reaction mixture, depending upon the molecular weight of the ultimate product to Other ex- 4 be produced. In the case of producing normally liquid and waxy polymers, the amount of promoter used varies between about 0.5 and about 10 weight percent of the monomer in the reaction mixture, with a preferred range between about 2 and about 6 weight percent of the monomer in the reaction mixture.

In general, it has been observed when producing polymers employing the aforementioned halogenated acyl peroxides, as promoters, an increase in the amount of promoter used, within the aforementioned range of concentral-ions, results in a decrease of the molecular weight of the resulting product. In the case of the solid plastic produced, the N. S. T. value is proportional to the molecular weight and therefore indicates, relatively, the molecular weight of the polymer produced. The N. S. T. value is defined as the no-strength-temperature of the solid polymer. l

A no-strength temperature (N. S. T.) between about 200 C. and about 350 C. is characteristic of a normally solid polymer, produced in accordance with the present process, having plastic characteristics. The most desirable plastic characteristics of the normally solid polymer are observed at N. S. T. values between about 240 and about 350. The no-strength-temperature (N. S. T.) is determined in the following manner:

A sample of poly-trifluorochloroethylene is hot pressed into at A thick sheet and is cut into a strip of Ms" K x 1%. This strip is notched 5 8 from the top of the strip so that the dimension at the notch is x A fine wire and a standard weight is attached to one end of the strip. a The weight of the solid polymer plus the wire and standard weight shall equal /2 gram. The strip is then attached in a furnace and fixed vertically therein. The temperature surrounding the sampleinside the furnace is increased at a rate of about 1 /2 C. per minute in the furnace as the breaking temperature is approached. The no-strength-temperature is the breaking temperature of the sample. Differences of about 5 C. are considered significant.

In producing normally solid polymers, in accordance with the present process, and since the peroxide promoter may be solid under normal conditions and substantially insoluble in the monomer, a solvent is usually employed to dissolve the promoter. The use of the promoter in the form of a solution facilitates handling and intimate admixture of the promoter with the monomer in the reaction zone. Preferred solvents are those which are non-reactive and have a boiling point higher than the boiling point of the monomer. The quantity of solvent containing the promoter employed, is usually between about 1 and about 20 percent of the monomer feed, however, larger or smaller amounts may be used without departing from the scope of the invention. A preferred solvent is trichlorofluoromethane. The solution of the promoter is maintained at a suffic-iently low temperature prior to introduction into the reaction zone in order to minimize decomposition.

When producing normally liquid and waxy polymers, in accordance with the present process, the polymerization of the monomer is also carried out in the presence of a chain-transfer solvent. The amount of chain-transfer solvent used varies between about 20 and about percent of the monomer in the reaction mixture. In general, an increase in the amounts of chain-transfer solvent results in a lower molecular weight of N. S. T. value of the resulting product of polymerization. A preferred chain-transfer solvent is chloroform, although other chain-transfer solvents may also be employed including carbon tetrachloride, bromotrichloromethane, trichlorotrifluoroethane, 1,2,2-tetrachloroethane, ethylene and saturated halogenated aliphatic compounds, in general, preferably containing bromine or chlorine.

The preparation of the above-mentioned trifiuorodichloropropionyl peroxide, as a promoter, is characteristic of the method for the preparation of the other halogensubstituted propionyl peroxides of this invention which contain only chlorine substitution. This. peroxide may be prepared by first forming trifluorodichloropropionyl chloride (CFsCClzCOCl). Trifiuorodichloropropionyl chloride is prepared by bubbling chlorine and oxygen through trifluorotrichloropropene (CF3CC1=CC12) in the presence of actinic radiation, (for example, ultraviolet light) to produce trifiuorodichloropropionyl chloride, as a liquid.

Liquid trifluorodichloropropionyl chloride thus produced, is next reacted with sodium peroxide (NazOz) suspended in aqueous sodium chloride solution (20% by weight or sodium chloride) to yield the desired trifluorodichloropropionyl peroxide. The quantity of trifluorodichloropropionyl chloride reacted with sodium peroxide is in accordance with stoichiometric requirements, although excess trifluorodichloropropionyl chloride may also be used. The reaction is carried out at a temperature in the range between about 20 C. and about (3., and preferably at a temperature of about l6 C., in an open mixing vessel at atmospheric pressure. Reaction takes place almost instantaneously.

The peroxide (trifluorodichloropropionyl peroxide) is recovered from the reaction mixture by extraction with Freonl1 (trichloromonofluoromethane). The peroxide crystallizes when the Freon solution is cooled to about -70 C. and is purified by washing and recrystallizing in fresh Freon-11. The purified peroxide is then dissolved in Freon-11 and diluted to the desired concentration for polymerization.

The following examples will serve to illustrate the method for the preparation of tn'fluorodichloropropionyl peroxide and may also be applied to the preparation of the other halogen-substituted propionyl peroxides of the present invention which contain only chlorine substitution.

Example I 21.6 grams of trifluorodichloropropionyl chloride (which is 3.4 grams in excess of the stoichiometric quantity) was reacted with 3.3 grams of sodium peroxide suspended in 248 grams of sodium chloride solution sodium chloride by weight) at 16 C. The above reaction produced a yield of 10.3 grams of trifluorodichloropropionyl peroxide.

Example 11 22 grams of perchloropropionyl chloride (which is the stoichiometric quantity) is reacted with 3.3 grams of sodium peroxide in 248 grams of sodium chloride solution (20% sodium chloride by weight) at l6 C. the above reaction produces a yield of 13 grams of perchloropropionyl peroxide.

In a manner similar to that shown in Examples 1 and II above, tetrachloropropionyl peroxide can be prepared by substituting tetrachloropropionyl chloride for either trifluorodichloropropionyl chloride or perchloropropionyl chloride when reacted with the stoichiometric quantity of sodium peroxide under the conditions set forth above.

As previously indicated, the homopolymerization or copolymerization of the perhalo-oleiin in the presence of any of the promoters is carried out under suitable conditions of temperature and residence time to produce the desired product. For the production of a plastic polymer, a temperature between about 20 C. and about 150 C. is employed. The preferred temperature is between about -20 C. and about 25 C. The pressure employed should in any case be at least in excess of the vapor pressure of the monomer at the polymerization temperature employed.

When polymerization is eifected under liquid phase conditions to produce a normally liquid polymer, a tem perature between about 0 C. and about 300 C. is employed, depending upon the particular chain-transfer solvent and operating conditions employed. A temperature between about 70 C. and about 200 C. is preferred.

A sutficiently high pressure at: the temperature of poly merization to maintain liquid phase conditions is em ployed. Excess pressures over those necessary to obtain liquid phase conditions may also be used, ranging as high as 15,000 or 30,000 pounds per square inch gage.

The residence time is defined as the length of time any particular polymerized monomer is retained in the polymerization zone. For the production of liquid or waxy polymers, the residence time to be allowed for completing the reaction and obtaining the desired product and yield, will range from a matter of seconds to as much as hours, preferably between about 1 minute and about 10 hours. The time of polymerization or residence time will affect both yield and molecular weight of the product. However, after a minimum residence time for a given temperature, the effect of continued. residence time is less pronounced and does not become a major factor. For example, at a temperature between about 0 C. and about 15 C. a minimum residence time of about 24 hours is required. For the production of a solid plastic polymer, longer periods of residence time are preferred and may range from a matter of minutes to about 8 days.

The use of inert diluents, such as water or hydrocarbon oils, in the polymerization reaction mixture as a meansfor heat removal and otherwise assuring a smoother reaction, is within the scope of the invention. In indicating concentrations of promoter and monomer, the presence of such diluents is not considered in reporting percentages, but only the presence of the active ingredients, such as monomer, promoter and chain-transfer solvent are considered.

Control of the concentrations may be accomplished by continuous or intermittent addition of the active components of the polymerization reaction as they are consumed or converted, in an amount sufficient to maintain their concentration substantially constant or within the preferred range. In the case of producing normally solid or plastic polymers, the promoter is consumed more rapidly than the monomer. Therefore, the promoter is added at a more rapid rate than the monomer, in con tinuous operations. In the production of normally liquid.

polymers, the monomer and promoter are consumed more rapidly than the chain-transfer solvent. Therefore, both monomer and promoter are added more rapidly than the chain-transfer solvent during a continuous polymerization process, in order to maintain their concentration at the desired value.

Example III The polymerization of trifluorochloroethylene is carried out in the presence of perchloropropionyl peroxide, as a promoter, in an amount of about 0.02 weight percent of the monomer in the reaction mixture, at a temperature of about 10 C. over a period of 24 hours. The polymer is produced in a yield of about 18 percent and has a N. S. T. value of approximately 290.

The other peroxides of this invention can be substituted in place of the peroxide of Example III to obtain similar results in eflecting the polymerization of trifluorochloroethylene.

Figures 1 and 2, graphically illustrating the results obtained over periods of 24 hours, indicate that the yield of polymer formed from the monomer trifluorochloroethylene, in accordance with the present process, is proportional to and the N. S. T. is inversely proportional to the peroxide concentration, employing trifiuorodichloropropionyl peroxide, as the promoter. It will be noted that the lower concentrations of the peroxide are much more efiicient in producing high N. S. T. polymer. An increase in the peroxide concentration of 13.5 times, will increase the polymer yield only about 3 times. The curves in these graphs also indicate the ease with which high yields of the polymer, having N. S. T. values between about 250 and about 275 C. can be obtained.

Figures 3 and 4 of the drawings illustrate the effect of temperature on the etficiency of the peroxide promoter for a given period of time in carrying out the polymerization of trifiuorochloroethylene as a monomer, in accordance with the present process. It will be noted that for a 24 hour period, the optimum temperature is about C. The N. S. T. temperature relationship is complicated by the initial formation of low molecular weightpolymers. The N. S. T. value is inversely proportional to the polymerization temperature. It will be noted from the curves in Figure 3 that the polymerization temperature has far less effect on the N. S. T. value than on the yield of polymer formed.

Figures 5, 6 and 7 of the drawing, illustrate the relationship between N. S. T. value, yield, and time when the concentration of promoter is the same in each case, to produce polymers of tritluorochloroethylenc in accordance with the process of the present invention. The curves in Figure 7 indicate the effect of temperature in reducing the low initial rate of polymerization. The curves in Figure 5 indicate the sharp increase in N. S. T. value which is proportional to the yield of polymer produced. Similar results are obtained by the use of the other peroxides of this invention.

From the above data, it will be seen that yields of trifluorochloroethylene polymer from about to about 40 percent, having N. S. T. values between about 250 C. and about 300 C., can be obtained in a period of 24 hours, by employing temperatures between about 10 C. and about C. to carry out the polymerization reaction, in the presence of trifiuorodichloropropionyl peroxide promoter.

Various modifications of the aforementioned process of the invention will be apparent to those skilled in the art without departing from the scope of the invention.

We claim:

1. A process for preparing perhalo-polymers which comprises polymerizing a perhalo-olefin at a temperature between about 20 C. and about 10 C. in the presence of a halogen-substituted propionyl peroxide selected from the group consisting of perchloropropionyl peroxide and tetrachloropropionyl peroxide, as a promoter, to produce a polymer of the perhalo-olefin as a product of the process.

2. A process in accordance with claim 1 in which the promoter comprises perchloropropionyl peroxide.

3. A process in accordance with claim 1 in which the promoter comprises tetrachloropropionyl peroxide.

4. A process for preparing perhalo-olefin polymers which comprises polymerizing a perhalo-olefin at a temperature between about 20 C. and about 10 C. in the presence of a halogen-substituted propionyl peroxide containing only chlorine substitution, as a promoter, for a time suificient to produce a polymer of the perhalo-olefin as a product of the process.

5. A process for preparing perhalo-olefin polymers which comprises polymerizing a perhalo-olefin at a temperature between about -20 C. and about 10 C. in the presence of a halogen-substituted propionyl peroxide containing only chlorine substitution, as a promoter, for a timesufficient to produce a polymer of the perhalo-olefin as a product of the process; and maintaining the concentration of the promoter between about .01 and about 10 percent of the perhalo-olefin in the reaction zone.

6. A process for preparing perhalo-olefin polymers which comprises polymerizing a perhalo-olefin at a temperature between about -20 C. and about 10 C. in the presence of a halogen-substituted propionyl peroxide containing only chlorine substitution, as a promoter, for a time sutficient to produce a liquid polymer of the perhaloolefin as a product of the process; and maintaining the concentration of the promoter between about 0.5 and about 10 percent of the perhalo-olefin in the reaction zone.

7. A process for preparing perhalo-olefin polymers which comprises polymerizing a perhalo-olefin at a temperature between about -20 C. and about 10 C. in the presence of a halogen-substituted propionyl peroxide containing only chlorine substitution, as a promoter, for a time sufiicient to produce a plastic polymer of the perhalo-olefin as a product of the process; and maintaining the concentration of the promoter between about 0.01 and about 0.5 percent of the perhalo-olefin in the reaction zone.

8. A process for preparing a trifiuorochloroethylene polymer which comprises polymerizing trifluorochloroethylene at a temperature between about -20 C. and about 10 C. in the presence of a halogen-substituted propionyl peroxide containing only chlorine substitution, as a promoter, for a time sufficient to produce a polymer of trifiuorochloroethylene as a product of the process.

9. A process for preparing a trifiuorochloroethylene polymer which comprises polymerizing trifluorochloroethylene at a temperature between about 20 C. and about 10 C. in the presence of perchloropropionyl peroxide, as a promoter, for a time suflicient to produce a polymer of trifluorochloroethylene as a product of the process.

10. A process for preparing a trifluorochloroethylene polymer which comprises polymerizing trifiuorochloroethylene at a temperature between about 20 C. and about 10 C. in the presence of tetrachloropropionyl peroxide, as a promoter, for a time sufiicient to produce a polymer of trifluorochloroethylene as a product of the process.

References Cited in the file of this patent UNITED STATES PATENTS 2,531,134 Kropa Nov. 21, 1950 2,559,630 Bullitt July 10, 1951 2,684,959 Rearick July 27, 1954 2,700,662 Young et a1. Jan. 25, 1955 2,705,706 Dittman et al. Apr. 5, 1955 

1. A PROCESS FOR PREPARING PERHALO-POLYMERS WHICH COMPRISES POLYMERIZATING A PERHALO-OLEFIN AT A TEMPERATURE BETWEEN ABOUT -20*C. AND ABOUT 10*C. IN THE PRESENCE OF A HALOGEN-SUBSTITUTED PROPIONYL PEROXIDE SELECTED FROM THE GROUP CONSISTING OF PERCHLOROPROPIONYL PEROXIDE AND 